From Xojo Documentation
New in 2011r2
A button control in a WebToolbar.
This item is similar to a normal toolbar button on the desktop. It can be clicked to fire an action, and can appear in a "toggled" style that makes it appear selected.
Click the "Pencil" icon to put the toolbar into edit mode. In edit mode you can add buttons and items to the toolbar using the "+" icon in the corner.
Clicking on individual toolbar items or buttons displays the properties you can edit. See the WebToolbar for information on how to create a toolbar that uses buttons and how to manage user input.